WO2022012166A1 - Safe train tracking and protection method and apparatus based on relative speed - Google Patents

Abstract

A safe train tracking and protection method and apparatus based on relative speed. The method comprises: step 1, a preceding train and a following train, which run in a tracked manner, respectively obtaining safe spatial-temporal trajectory information of the trains during a stopping process by using an electronic map and autonomous speed measurement and location information in combination with the performance of the trains (S11); step 2, the following train obtaining the safe spatial-temporal trajectory information of the preceding train by using a vehicle-to-vehicle communication means (S12); step 3, in view of the safe spatial-temporal trajectory information of the preceding train and the following train, the following train creating a safety condition according to the constraint that the position of the following train cannot surpass the position of the preceding train at any time, and solving an emergency brake intervention (EBI) speed of the following train (S13); and step 4, the following train determining, by means of comparison, whether the current measured speed v₂(t₀) of the following train exceeds the EBI speed E₂(t₀) of the following train, and if v₂(t₀)＞E₂(t₀), outputting an emergency brake instruction to make the following train decelerate until the following train stops (S14).

Description

A kind of train safety tracking protection method and device based on relative speed technical field

The invention relates to the field of traffic, and in particular to a relative speed-based train safety tracking protection method and device.

Background technique

With the development of my country's national economy and the acceleration of urbanization, rail transit is facing the need to transport more passengers and goods and has become an important means to relieve traffic pressure. As the "brain and nerve center" of rail transit, the control goal of the train operation control system is to ensure that the train runs efficiently under the premise of ensuring safety.

In the current train control system based on mobile block, there are theoretically two ways of "hitting a hard wall" (thinking that the vehicle in front stops instantaneously) and "hitting a soft wall" (considering tracking the relative speed between trains) to protect the train from overspeed. When using the "hit hard wall" model, the movement authorization end point of the rear vehicle (the position that the rear vehicle is absolutely not allowed to cross) is set to the rear position of the front vehicle (a protective distance can also be considered). The Automatic Train Protection (ATP) protects the train from running within the scope of the Movement Authority (MA) and ensures that the train position does not exceed the limit of the MA terminal. Under the "hit hard wall" model, the train interval is controlled based on the absolute braking distance of subsequent trains, that is, d=d _brake2 +S, where d is the safe tracking distance between the two trains; d _brake2 is the braking distance of the rear train ; S is the safety distance margin. Therefore, from the moment when the rear car receives the MA that ends at the tail of the preceding train, the running trajectories of the two trains do not have the possibility of crossing. To ensure that the rear car does not exceed the speed limit, it can ensure that the rear car does not pass the limit of the MA end point, so as to ensure the safety of the train tracking operation (no rear-end collision). However, in this way, the tracking interval of trains is required to be relatively large, which limits the performance of the line's transport capacity and makes it difficult to meet the demand for continuous and rapid growth of passenger flow.

Compared with the "hit a hard wall" method, the "hit a soft wall" method utilizes the speed and braking process information of the preceding train, thereby shortening the train tracking interval and improving the tracking efficiency. When the preceding train has a certain speed, the MA end point of the following train is no longer set to the tail of the preceding train (considering a certain safety distance margin), but can be based on the estimated forward running distance of the preceding train. The guard point of the train is set to a certain position before the tail position of the preceding train at the current moment (represented by p in this paper), so that the train tracking interval can be shortened. In the existing literature, the position at the stopping time of the preceding train is usually estimated as the above-mentioned position p, and this position is regarded as the MA end point of the following train, and the maximum position limit that the following train can reach at the stopping time (the head of the following train) is obtained accordingly. The position cannot exceed the rear position of the preceding train, and a certain protection distance margin is considered), and then combined with the braking distance of the subsequent train during the parking process, the minimum safe tracking interval between the subsequent train and the preceding train can be calculated, that is, d= d _brake2 -d _brake1 +S, in the formula, d _brake1 is the braking distance of the preceding vehicle; d is the safe tracking distance between the two trains; d _brake2 is the braking distance of the rear vehicle; S is the safety distance margin. The above formula specifies the minimum distance between the two trains under the premise of safety when the speed of the preceding train and the following train are determined. In practice, according to the distance of the front and rear tracked trains and the speed of the preceding train, combined with the line parameters and the safe braking model of the two trains (including the description of the train braking process under the most unfavorable conditions, performance parameters, etc.), it can be calculated. Obtain the emergency braking trigger (EBI) speed of the subsequent train, and protect the actual speed of the train, that is, if the actual speed of the subsequent train exceeds the EBI speed, the emergency braking is output to decelerate the train to a stop, so as to ensure that the rear car stops After the actual position does not exceed the limit of the above target position. Obviously, the "hit soft wall" model can effectively shorten the minimum safe tracking interval distance of trains.

However, the above method of "hitting into a soft wall" only considers the positional relationship between the two cars at the parking time, and does not consider the safety requirements of the full-time positional relationship during the train operation, so that when the performance parameters and initial speeds of the front and rear cars are different, There is a safety hazard in a rear-end collision. Figure 1 shows the comparison between the "hit a hard wall" and "hit a soft wall" model and the hidden dangers of the above methods. The following is a detailed description of the scenario in which the "hitting against a soft wall" method has potential safety hazards.

It can be seen from the calculation formula of the train safety tracking interval in the "hit soft wall" mode (ie d=d _brake2 -d _brake1 +S), when d _brake2 < d _brake1 , the train tracking interval obtained in this way may be less than the minimum value. The safety distance margin is even less than 0 (ie d<0), so there is a safety hazard. Further analysis shows that when the initial speed of the front car is low but the braking acceleration is small (slow deceleration), and the initial speed of the rear car is high but the braking acceleration is large (fast deceleration), the distance between the two cars will first decrease and then increase, so The variation of the distance between the two vehicles is non-monotonic, and the minimum distance between the two vehicles does not necessarily occur at the parking time. Therefore, the existing "hit soft wall" method only considers the constraints that the two vehicles do not collide at the parking time, which is not enough to ensure the safety of the whole process of train tracking.

SUMMARY OF THE INVENTION

The embodiments of the present invention provide a relative speed-based train safety tracking protection method and device, which can ensure the entire tracking process under any combination of performances of the front and rear trains by considering the safety constraints of the space-time trajectories of the front and rear trains in the whole process of train tracking. safety and avoid rear-end collisions.

A train safety tracking protection method based on relative speed, comprising:

Step 1, track the running vehicle in front and the rear by using the electronic map and autonomous speed measurement and positioning information combined with the performance of the train to obtain the safety space-time trajectory information of the train during the parking process respectively; the safety space-time trajectory information includes: position changes with time curve;

Step 2, using the vehicle-to-vehicle communication method, the rear vehicle obtains the safety space-time trajectory information of the preceding vehicle;

Step 3, the rear vehicle combines the safety space-time trajectory information of the front vehicle and the rear vehicle, establishes a safety condition according to the constraint that the position of the rear vehicle cannot exceed the position of the preceding vehicle at any time, and solves the emergency of the rear vehicle. Braking triggers EBI speed;

Step 4, the rear vehicle compares _{whether the current measured speed v 2} (t ₀ ) of the rear vehicle exceeds the EBI speed E ₂ (t ₀ ) of the rear vehicle; if v ₂ (t ₀ )>E ₂ (t ₀ ), the emergency braking command is output to make the rear vehicle decelerate to a stop.

A train safety tracking protection device based on relative speed, comprising:

The first generating unit is used to track the running vehicle in front and the rear vehicle to obtain the safety space-time trajectory information of the train during the parking process by using the electronic map and the autonomous speed measurement and positioning information in combination with the train performance; the safety space-time trajectory information includes: position curve over time;

an acquisition unit, using the communication method between vehicles, the rear vehicle obtains the safety space-time trajectory information of the front vehicle;

Solving unit, the rear vehicle combines the safety space-time trajectory information of the front vehicle and the rear vehicle, establishes a safety condition according to the constraint that the position of the rear vehicle cannot exceed the position of the preceding vehicle at any time, and solves the emergency of the rear vehicle Braking triggers EBI speed;

A comparison unit, the rear vehicle compares _{whether the current measured speed v 2} (t ₀ ) of the rear vehicle exceeds the EBI speed E ₂ (t ₀ ) of the rear vehicle; if v ₂ (t ₀ )>E ₂ (t ₀ ), the emergency braking command is output to make the rear vehicle decelerate to a stop.

It can be seen from the technical solutions provided by the above embodiments of the present invention that in the embodiments of the present invention, by adopting the vehicle-to-vehicle communication system and the overspeed protection design method, the train safety tracking protection based on relative speed can be realized to avoid rear-end collision accidents.

Additional aspects and advantages of the present invention will be set forth in part in the following description, which will be apparent from the following description, or may be learned by practice of the present invention.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

Figure 1 is a schematic diagram of the comparison between the "hit a hard wall" and "hit a soft wall" model;

2 is a schematic flowchart of the relative speed-based train safety tracking protection method according to the present invention;

Fig. 3 is the calculation flow chart of the emergency braking trigger speed EBI speed of the rear vehicle in the present invention;

FIG. 4 is a flow chart of a specific implementation of the relative speed-based train safety tracking protection method of the present invention.

FIG. 5 is a structural diagram of the relative speed-based train safety tracking protection device according to the present invention.

detailed description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but not to be construed as a limitation of the present invention.

It will be understood by those skilled in the art that the singular forms "a", "an", "the" and "the" as used herein can include the plural forms as well, unless expressly stated otherwise. It should be further understood that the word "comprising" used in the description of the present invention refers to the presence of stated features, integers, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other features, Integers, steps, operations, elements, components and/or groups thereof. It will be understood that when we refer to an element as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Furthermore, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as herein, are not to be taken in an idealized or overly formal sense. explain.

To facilitate the understanding of the embodiments of the present invention, the following will take a plurality of specific embodiments as examples for further explanation and description in conjunction with the accompanying drawings, and each embodiment does not constitute a limitation to the embodiments of the present invention.

The processing flow of a relative speed-based train safety tracking protection method provided by an embodiment of the present invention is shown in FIG. 2 , and includes the following processing steps:

Step 11, the tracked leading and trailing vehicles use electronic maps and autonomous speed measurement and positioning information combined with train performance to obtain the safety space-time trajectory information of the train in the parking process; the safety space-time trajectory information includes: position changes over time; curve;

Step 12, using the communication method between vehicles, the rear vehicle obtains the safety space-time trajectory information of the preceding vehicle;

In step 13, the rear vehicle combines the safety space-time trajectory information of the preceding vehicle and the rear vehicle, establishes a safety condition according to the constraint that the position of the rear vehicle cannot exceed the position of the preceding vehicle at any time, and solves the emergency of the rear vehicle. Braking triggers EBI speed;

Step 14, the rear vehicle compares _{whether the current measured speed v 2} (t ₀ ) of the rear vehicle exceeds the EBI speed E ₂ (t ₀ ) of the rear vehicle; if v ₂ (t ₀ )>E ₂ (t ₀ ), the emergency braking command is output to make the rear vehicle decelerate to a stop.

The step 11 specifically includes:

_{The preceding vehicle obtains its own speed v 1} (t ₀ ) and position information x ₁ (t ₀ ) by using the speed measurement and positioning technology, and the rear vehicle obtains its own speed v ₂ (t ₀ ) and position information x ₂ ( t ₀ );

The leading vehicle obtains the most unfavorable gradient acceleration β ₁ and the maximum emergency braking acceleration α ₁ during the emergency braking process, and the rear vehicle obtains the most unfavorable gradient acceleration β ₂ during the period from triggering emergency braking to stopping, and the traction phase duration δ ₂ , maximum traction acceleration value γ ₂ , coasting phase duration ε _{2 , emergency braking acceleration α 2} that can be guaranteed under the most unfavorable conditions;

The preceding vehicle takes the actual measured vehicle rear position and speed information as the initial state, and calculates the position change with time during the train braking process according to the model that the train immediately implements emergency braking, combined with the train braking performance and line parameters obtained by the query. the curve;

The rear car takes the actual measured train head position information and EBI speed as the initial state, according to the safety braking model specified by IEEE1474. A plot of position versus time.

The step 13 specifically includes:

Step 131: Calculate the duration τ _{1 of the} braking phase of the preceding vehicle, that is,

Step 132: According to the braking phase duration τ ₁ of the preceding vehicle, the traction phase duration δ ₂ of the preceding vehicle, the coasting phase duration ε ₂ of the preceding vehicle, the braking phase duration τ _{1 of the} preceding vehicle, the maximum emergency braking acceleration α ₁ , the preceding vehicle is in emergency most unfavorable braking process gradient acceleration β _1, after the emergency braking acceleration α under the most unfavorable conditions to ensure that the vehicle _2, the vehicle from the most negative slope during braking to trigger an emergency stop acceleration beta] _2, is determined after Calculation method of car EBI speed.

When τ ₁ <δ ₂ +ε ₂ , the constraint condition for calculating the initial speed of the rear vehicle, that is, v ₂ (t ₀ )≤f ₅ (t) and v ₂ (t ₀ )≤f ₄ (t _m1 ), the rear vehicle The calculation method of EBI speed is: E ₂ (t ₀ )=min(f ₅ (t), f ₄ (t _m1 ))

When δ ₂ +ε ₂ ≤τ ₁ , and (α ₁ +β ₁ )-(α ₂ +β ₂ )>0, calculate the constraints of the initial speed of the rear vehicle respectively, v ₂ (t ₀ )≤f ₅ ( t), v ₂ (t ₀ )≤f ₄ (t _m1 ), v ₂ (t ₀ )≤f ₄ (t ₁ ) and v ₂ (t ₀ )≤f ₃ (t _n1 ); The calculation method is: E ₂ (t ₀ )=min(f ₅ (t), f ₄ (t _m1 ), f ₄ (t ₁ ), f ₃ (t _n1 ))

When δ ₂ +ε ₂ ≤τ ₁ , and (α ₁ +β ₁ )-(α ₂ +β ₂ )≤0, calculate the constraint conditions for the initial speed of the rear vehicle, namely v ₂ (t ₀ )≤f ₅ (t), v ₂ (t ₀ )≤f ₄ (t _m1 ) and v ₂ (t ₀ )≤f ₄ (t ₁ ), the calculation method of the EBI speed of the following vehicle is: E ₂ (t ₀ )=min( f ₄ (t ₁ ), f ₅ (t), f ₄ (t _m1 )).

The application scenarios of the present invention are described below.

The invention proposes a train safety tracking protection method based on relative speed, which not only ensures full-time and space safety (no rear-end collision) during the tracking process of two cars, but also fully considers the actual state and braking distance of the preceding train, thereby Shorten the train tracking interval, improve the transportation efficiency of the rail transit system, promote the development of the safety protection technology of the urban rail train system, ensure the safety of the train in the full range of time and space, and avoid the occurrence of rear-end collisions. The invention is based on a train-to-train control system, and realizes the purpose of high-density safety tracking of trains by clarifying the content of information transmitted during train-to-vehicle communication and the specific use method of the information. The method of overspeed protection for subsequent trains based on tracking the relative speed between trains can be applied to rail traffic signal safety protection technology.

Tracking trains with vehicle-to-vehicle communication can realize autonomous speed measurement and positioning, and establish an end-to-end communication link between adjacent trains (the specific communication system is not limited, and point-to-point direct vehicle-to-vehicle communication can be used, or WLAN, LTE or 5G communication channel). The electronic map of the line data is stored in the on-board controller of the train, and various required line parameter information (such as line gradient acceleration) can be inquired. In order to achieve the purpose of high-density and safe tracking of trains, the process for the interaction and use of tracked train information is designed as follows:

The content transmitted between adjacent trains should include information such as train ID, train position, train speed, and the space-time trajectory of the train in the "most favorable" situation; Under the conditions of speed, train performance parameters and line parameters, the position-time function curve formed by running in the fastest braking and stopping mode.

According to the relevant parameters of the train control factors that can make the train stop the fastest, the preceding train calculates the space-time trajectory of the train in the "most favorable" condition according to the model that has implemented the maximum emergency braking. Among them, the maximum emergency acceleration of the train is taken according to the maximum emergency braking value in the train performance parameters provided by the vehicle system; the line gradient acceleration during the braking process is taken according to the gradient acceleration of the maximum up-slope that the train may be in during the braking process. The value (that is, the acceleration that makes the train stop faster), when there is no upward slope but there is a flat slope, the value is taken according to the flat slope; otherwise, it is taken according to the minimum value of all the downward slopes; for the convenience of description, this article collectively refers to for "Maximum Up Ramp".

The preceding train sends the calculated and generated space-time trajectory under the "most favorable" situation to the following train together with the train ID, position and speed and other information;

After the subsequent train receives the information of the preceding train, it will be regarded as the protection target curve that cannot be crossed during the operation;

According to the train braking model stipulated in the IEEE1474.1 standard, the following trains calculate the space-time trajectory curve under the "most unfavorable" condition of the train, that is, the running process curve of the slowest stop of the train when the emergency braking is output immediately; Among them, when the subsequent train calculates the space-time trajectory curve under the "most unfavorable" situation, the train braking acceleration is based on the "most unfavorable" emergency braking acceleration, and the line gradient acceleration during the train braking process is based on the maximum downhill acceleration. .

The following train compares the space-time trajectory curve under the "most unfavorable" situation of the current train with the space-time trajectory curve under the "most favorable" situation of the preceding train, to ensure that the position of the preceding train at any time (that is, the maximum front end position of the following train) ) does not exceed the value of the position of the latter at the corresponding time (that is, the maximum safe rear end of the preceding vehicle), so as to ensure the safety of the train tracking operation. Since the space-time trajectory curve under the "most favorable" situation of the subsequent train is related to its "initial speed", under the premise of ensuring the above safety, the maximum value of the "initial speed" calculated by the subsequent train is the safety protection speed (also known as the safety protection speed) calculated by the subsequent train. called emergency braking trigger speed).

Subsequent trains compare the actual speed of the train with the calculated emergency braking triggering speed. When the actual speed exceeds the emergency braking triggering speed, the emergency braking is output to stop the train, thereby ensuring that no rear-end collision occurs during the train tracking process. .

In the actual multi-vehicle tracking process, any train in the middle can be used as the front car of its subsequent train, or it can be used as the rear car of its previous train, which can complete the functions of the previous train and the following train at the same time, so as to achieve high train density. Safe tracking runs.

In addition to the specific content and processing principles of vehicle-to-vehicle communication, the core content of the invention is the running process model of the preceding train and the following train, and the proposed emergency braking trigger speed of the rear vehicle for full-time and space-time collision avoidance. calculation method.

The mathematical model of the running process of the front and rear trains and the specific calculation method of the emergency braking trigger speed of the train will be described below.

1. Analysis and modeling of train safety tracking process

According to the actual experience in the design of the train protection system, when the front vehicle uses the maximum emergency braking to stop, and the rear vehicle uses the safe braking model specified in the IEEE 1474.1 standard, it corresponds to the safety boundary conditions when the two vehicles are tracking. Therefore, a two-train safety tracking model is established based on this condition.

1) Two-train tracking process model

According to the above-mentioned safety boundary conditions, the running process of the preceding vehicle is linear motion with uniform acceleration, and the running process of the following vehicle is linear motion with segmented uniform acceleration. All occurrences of Train 1 below refer to the preceding car and Train 2 to the following car. The following is an example of running along the positive direction of the train line (the position of the train increases along the running direction) as an example (the reason for running in the opposite direction of the line is similar). The running process of the preceding train can be described by the following formula:

In the formula, a ₁ (t) is the acceleration of the preceding vehicle at any time; α ₁ is the maximum emergency braking acceleration (constant) of the preceding vehicle (train 1); β ₁ is the most unfavorable acceleration of the preceding vehicle during the emergency braking process. Slope (uphill) acceleration (constant); t _b is the time value when both trains stop; t ₁ is the time value when the preceding vehicle stops, satisfying t ₁ =t ₀ +τ ₁ (where τ ₁ is the braking of the preceding vehicle time, satisfied

On this basis, the speed and rear position of the preceding vehicle at any time can be obtained, as shown in formulas (2) and (3), respectively:

According to the train safety braking model, the rear car has experienced three stages: traction, coasting (without traction and braking acceleration, but may be in an accelerated state due to the influence of gradient acceleration), and emergency braking. The acceleration of the rear car at any time is shown in the formula (4) shows:

Wherein a ₂ (t) is the acceleration of the car at any time; γ ₂ is the maximum traction vehicle acceleration value when emergency braking is triggered (constant); β ₂ from the vehicle during a parking after triggering an emergency brake to the the most unfavorable slope (downhill) acceleration (constant); α ₂ of the car on straight track, under the most unfavorable conditions to ensure that the emergency braking acceleration (constant); b ₂ after the termination phase traction vehicle time (i.e. start the coasting phase); c ₂ is the time at which the coasting phase of the rear vehicle ends (that is, the moment when the emergency braking is started); t ₂ is the time when the rear vehicle emergency brakes and stops.

The speed of the rear car at any time can be obtained, as shown in formula (5):

In the formula,

for the trailing vehicle at the end of towing

The speed value of , which satisfies:

In the formula, δ ₂ is the duration of the traction stage of the rear vehicle, which satisfies δ ₂ =b ₂ -t ₀ ; v ₂ (c ₂ ) is the speed value of the rear vehicle at the end time c ₂ of coasting, which satisfies:

v ₂ (c ₂ )=v ₂ (b ₂ )+β ₂ ε ₂ (7)

In the formula, ε ₂ is the duration of the coasting phase of the rear vehicle, which satisfies: ε ₂ =c ₂ -b ₂ .

Further, the head position of the rear car at any time can be obtained, as shown in formula (8):

In the formula, x ₂ (b ₂ ) is the position of the rear vehicle at the time b ₂ when the traction ends, which satisfies:

In the formula, x ₂ (c ₂ ) is the position of the rear vehicle at the time c ₂ at the end of coasting, which satisfies:

2) Constraints of safety conditions for train tracking operation

According to the basic assumption that the train's position along the running direction of the train is increasing, and the basic knowledge of the safe tracking operation of the train, the safety conditions to ensure that the train does not have a rear-end collision can be described as:

x ₂ (t)≤x ₁ (t)-S,t∈[t ₀ , t _b ] (11)

In the formula, S is the protection distance margin (constant); the above formula indicates that the distance between the front position of the rear vehicle and the rear position of the preceding vehicle at any time cannot be less than the protection distance margin, so as to ensure the safety of train tracking. It should be noted that, according to the needs of the shortest tracking interval, the minimum distance between the two trains should be minimized (that is, when the minimum distance between the two trains is exactly equal to S, the train tracking efficiency is the highest).

3) Calculation method of emergency braking trigger speed of rear car

The emergency braking trigger (EBI) curve of the rear car should be the maximum speed calculated according to the state of the front and rear trains to ensure the safe operation of the rear car. Therefore, the EBI curve of the rear vehicle should be solved according to the following ideas:

A. First define the train separation distance at any time as d(t)=x ₁ (t)-x ₂ (t);

B. According to the constraint condition that the distance between trains must be greater than the specified safety protection distance during the operation of the train, d(t)≥S is obtained;

C. According to the above constraints, _{the inequality constraints related to the initial speed of the rear vehicle v 2} (t ₀ ) and v ₁ (t ₀ ), x ₂ (t ₀ ), and x ₁ (t ₀ ) can be calculated and obtained, assuming that it can be recorded is v ₂ (t ₀ )≤f _n (v ₁ (t ₀ ), x ₂ (t ₀ ), x ₁ (t ₀ )); among them, f _n () indicates that a certain functional relationship is satisfied; at this time, the obtained The maximum value of v ₂ (t ₀ ) is the emergency braking trigger speed of the train.

D. The f _n ( ) obtained in practice is a collection of a series of functions, and the minimum value of all functions needs to be obtained according to the train classification conditions, as the emergency brake trigger (Emergency Brake Intervention, EBI) speed of the train. The specific calculation process is shown in Figure 3. Among them, formula 1:

in,

In formula 2,

in,

Formula 3:

Formula 4:

in,

According to the above process, the following train can calculate and obtain the EBI speed of the following train according to the position, speed and performance parameters of the preceding train and the position and performance parameters of the following train, which can be used as the safety limit for the train to implement overspeed protection (actual speed). When the EBI speed is exceeded, the rear car outputs emergency braking to decelerate the train to a stop).

Below in conjunction with the drawings, the specific embodiments of the present invention will be further described:

In the train operation control system, the Vehicle On-Board Controller (VOBC) has the function of autonomous train speed measurement and positioning. VOBC can not only safely and accurately measure the train's position and running status information on the line, but also obtain line-related information in combination with the internal stored electronic map, as an important supplement to train positioning. In the train control system of train-to-vehicle communication, with the help of high-precision positioning and low-latency and large-capacity communication technology, trains can transmit information such as speed, position, acceleration, and train space-time trajectory through direct or indirect wireless communication. In addition, the train runs under the protection of ATP, ATP calculates the EBI speed according to the running state of the tracked train, and compares the train speed with the calculated EBI speed. When an overspeed event occurs, ATP will immediately implement emergency braking to slow down the train until parking.

In the present invention, in order to shorten the train tracking interval as much as possible, the preceding train needs to estimate the time-space trajectory of the braking process under the "most favorable" condition of the vehicle and send it to the rear vehicle as the safety protection target of the rear vehicle; the rear vehicle must calculate the "most favorable" condition of the vehicle. “Unfavorable” space-time trajectory, and according to the safety protection target of the preceding vehicle, the EBI speed is calculated according to the principle of full-time space-time collision avoidance. The present invention is mainly based on the train control system of vehicle-to-vehicle communication, but is also applicable to the traditional CBTC system in which the information of the preceding vehicle needs to be transferred through a ground zone controller (Zone Controller, ZC).

The specific flow of the implementation of the present invention will be described below.

Tracking the train (including tracking the preceding and following cars) uses the electronic map and autonomous speed measurement and positioning information combined with the performance of the train to obtain the safe space-time trajectory information of the train during the parking process. Specifically:

The train can obtain its speed and position information by using the speed measurement and positioning technology. For example, train 1 (the front car) can obtain its own speed and position information: v ₁ (t ₀ ), x ₁ (t ₀ ), and train 2 (the rear car) can obtain its own speed and position information. Obtain own speed and position information: v ₂ (t ₀ ), x ₂ (t ₀ );

Using the electronic map and train performance parameter information stored on the vehicle, the train can query the line gradient acceleration and train traction/braking performance parameters in real time. Acceleration β ₁ , maximum emergency braking acceleration α ₁ , train 2 (rear train) can obtain the most unfavorable gradient acceleration β ₂ from triggering emergency braking to stopping, traction phase duration δ ₂ , maximum traction acceleration value γ ₂ , coasting Stage duration ε _{2 , emergency braking acceleration α 2} that can be guaranteed under the most unfavorable conditions, etc.;

Taking the actual measured position and speed of the rear of the car as the initial state, according to the model that the train immediately implements emergency braking, combined with the train braking performance and line parameters obtained by the query, calculate the curve of the position change with time during the train braking process ; The rear car takes the actual measured train head position information and the variable to be solved (EBI speed) as the initial state, according to the safety braking model specified by IEEE1474.1, combined with the train traction, braking performance and line parameters obtained by query, calculate the train The curve of position change with time during braking;

The following vehicle can directly obtain the position, speed and acceleration information of the preceding vehicle, namely v ₁ (t ₀ ), x ₁ (t ₀ ), β ₁ , α ₁ , by means of direct or indirect communication between the vehicles.

Using direct or indirect communication between vehicles, the rear vehicle obtains the spatiotemporal trajectory information (the curve of the position changing with time) calculated by the preceding vehicle;

Combined with the spatiotemporal trajectory information of the preceding vehicle and own vehicle, the rear vehicle establishes a safety condition (i.e. x ₂ (t)≤x ₂ (t)-S) according to the constraint that the position of the rear vehicle cannot exceed the position of the preceding vehicle at any time, and solves the problem. EBI speed of the following vehicle. That is, by substituting the initial state information (v ₁ (t ₀ ), x ₂ (t ₀ ), and x ₁ (t ₀ )) of the preceding and following vehicles into the formula for calculating the _{EBI speed E 2} (t _{0 ) of the following vehicle, we can obtain} The EBI value of the following vehicle at the initial moment. In practice, according to the actual parameters and initial states of the front and rear vehicles, the formula for EBI calculation is also different, and the corresponding calculation function should be selected according to different conditions. The specific classification conditions and calculation functions are as follows:

First, calculate the duration τ _{1 of the} preceding vehicle braking phase, that is,

According to the _{relationship between τ 1} , δ ₂ , and ε ₂ , the solution to the EBI speed E ₂ (t ₀ ) of the following vehicle can be divided into the following two cases:

When τ ₁ <δ ₂ +ε ₂

According to the formula (1) and formula (2) of Fig. 4, the constraint conditions of the initial speed of the rear vehicle are calculated, that is, v ₂ (t ₀ )≤f ₅ (t) and v ₂ (t ₀ )≤f ₄ (t _m1 ). At this time, the calculation method of the EBI speed of the following vehicle is:

E ₂ (t ₀ )=min(f ₅ (t),f ₄ (t _m1 ))

When δ ₂ +ε ₂ ≤τ ₁ , first determine the magnitude relationship between the braking performance of the front and rear trains:

①If (α ₁ +β ₁ )-(α ₂ +β ₂ )>0, calculate the constraints on the initial speed of the rear vehicle according to formulas (1) to (4) in Fig. 4, namely v ₂ (t ₀ )≤ f ₅ (t), v ₂ (t ₀ )≤f ₄ (t _m1 ), v ₂ (t ₀ )≤f ₄ (t ₁ ) and v ₂ (t ₀ )≤f ₃ (t _n1 ). At this time, the calculation method of the EBI speed of the following vehicle is:

E ₂ (t ₀ )=min(f ₅ (t), f ₄ (t _m1 ), f ₄ (t ₁ ), f ₃ (t _n1 ))

②If (α ₁ +β ₁ )-(α ₂ +β ₂ )≤0, calculate the constraints of the initial speed of the rear vehicle according to formulas (1) to (3) in Fig. 4, namely v ₂ (t ₀ )≤ f ₅ (t), v ₂ (t ₀ )≦f ₄ (t _m1 ) and v ₂ (t ₀ )≦f ₄ (t ₁ ). At this time, the calculation method of the EBI speed of the following vehicle is:

E ₂ (t ₀ )=min(f ₄ (t ₁ ), f ₅ (t), f ₄ (t _m1 ))

Use the EBI curve to protect the train from overspeed, that is, compare _{whether the current measured speed v 2} (t ₀ ) of the rear vehicle exceeds the EBI speed E ₂ (t ₀ ), if v ₂ (t ₀ )>E ₂ (t ₀ ), output Emergency braking slows the train to a stop to avoid a rear-end collision of the train.

By using the train-to-vehicle communication system and the above-mentioned overspeed protection design method, the train safety tracking protection based on relative speed can be realized, and the train tracking interval can be shortened to the maximum extent and the transportation efficiency of the urban rail system can be improved on the premise of ensuring no rear-end collision accident.

A structure diagram of a relative speed-based train safety tracking protection device provided by an embodiment of the present invention is shown in FIG. 5 , including:

The first generating unit is used to track the running vehicle in front and the rear vehicle to obtain the safety space-time trajectory information of the train during the parking process by using the electronic map and the autonomous speed measurement and positioning information in combination with the train performance; the safety space-time trajectory information includes: position curve over time;

an acquisition unit, using the communication method between vehicles, the rear vehicle obtains the safety space-time trajectory information of the front vehicle;

Solving unit, the rear vehicle combines the safety space-time trajectory information of the front vehicle and the rear vehicle, establishes a safety condition according to the constraint that the position of the rear vehicle cannot exceed the position of the preceding vehicle at any time, and solves the emergency of the rear vehicle Braking triggers EBI speed;

A comparison unit, the rear vehicle compares _{whether the current measured speed v 2} (t ₀ ) of the rear vehicle exceeds the EBI speed E ₂ (t ₀ ) of the rear vehicle; if v ₂ (t ₀ )>E ₂ (t ₀ ), the emergency braking command is output to make the rear vehicle decelerate to a stop.

The specific process of using the apparatus of the embodiment of the present invention to perform the train safety tracking protection based on the relative speed is similar to the foregoing method embodiment, and will not be repeated here.

The beneficial effects of the present invention are as follows:

1. Compared with the traditional "hit a hard wall" tracking protection method, the train tracking distance is effectively shortened on the basis of ensuring safety, and the system transportation capacity is improved;

2. Compared with the "hitting soft wall" model in the background art, the safety of full-time tracking of trains with any combination of performances can be ensured, and the occurrence of rear-end collisions can be avoided.

Those of ordinary skill in the art can understand that the accompanying drawing is only a schematic diagram of an embodiment, and the modules or processes in the accompanying drawing are not necessarily necessary to implement the present invention.

Those of ordinary skill in the art can understand that the components of the apparatus in the embodiment may be distributed in the apparatus of the embodiment according to the description of the embodiment, or may be located in one or more apparatuses different from the embodiment with corresponding changes. The components of the above-mentioned embodiments may be combined into one component, or may be further divided into multiple sub-components.

Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the various embodiments may be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the apparatus or system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and reference may be made to some descriptions of the method embodiments for related parts. The apparatus and system embodiments described above are only illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, It can be located in one place, or it can be distributed over multiple network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution in this embodiment. Those of ordinary skill in the art can understand and implement it without creative effort.

The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. Substitutions should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (6)

1. A kind of train safety tracking protection method based on relative speed, it is characterized in that, comprising:

   In step 1, the preceding and following vehicles are tracked to obtain the safe space-time trajectory information of the train during the parking process by using the electronic map and the autonomous speed measurement and positioning information combined with the train performance; the safe space-time trajectory information includes: curve;

   Step 2, using the vehicle-to-vehicle communication method, the rear vehicle obtains the safety space-time trajectory information of the preceding vehicle;

   Step 3, the rear vehicle combines the safety space-time trajectory information of the front vehicle and the rear vehicle, establishes a safety condition according to the constraint that the position of the rear vehicle cannot exceed the position of the preceding vehicle at any time, and solves the emergency of the rear vehicle. Braking triggers EBI speed;

   Step 4, the rear vehicle compares _{whether the current measured speed v 2} (t ₀ ) of the rear vehicle exceeds the EBI speed E ₂ (t ₀ ) of the rear vehicle; if v ₂ (t ₀ )>E ₂ (t ₀ ), the emergency braking command is output to make the rear vehicle decelerate to a stop.
2. The method of claim 1, comprising: the step 1 comprises;

   _{The preceding vehicle obtains its own speed v 1} (t ₀ ) and position information x ₁ (t ₀ ) by using the speed measurement and positioning technology, and the rear vehicle obtains its own speed v ₂ (t ₀ ) and position information x ₂ ( t ₀ );

   The leading vehicle obtains the most unfavorable gradient acceleration β ₁ and the maximum emergency braking acceleration α ₁ during the emergency braking process, and the rear vehicle obtains the most unfavorable gradient acceleration β ₂ during the period from triggering emergency braking to stopping, and the traction phase duration δ ₂ , maximum traction acceleration value γ ₂ , coasting phase duration ε _{2 , emergency braking acceleration α 2} that can be guaranteed under the most unfavorable conditions;

   The preceding vehicle takes the actual measured vehicle rear position and speed information as the initial state, and calculates the position change with time during the train braking process according to the model that the train immediately implements emergency braking, combined with the train braking performance and line parameters obtained by the query. the curve;

   The rear car takes the actual measured train head position information and EBI speed as the initial state, according to the safety braking model specified by IEEE1474. A plot of position versus time.
3. The method according to claim 1, wherein the step 3 comprises:

   Step 31: Calculate the duration τ _{1 of the} braking stage of the preceding vehicle, that is,

   

   Step 32: According to the duration τ _{1 of the preceding vehicle braking phase, the duration δ 2 of the} preceding vehicle traction phase, the preceding vehicle coasting phase duration ε ₂ , the preceding vehicle braking phase duration τ ₁ , the maximum emergency braking acceleration α ₁ , the preceding vehicle is in emergency most unfavorable braking process gradient acceleration β _1, after the emergency braking acceleration α under the most unfavorable conditions to ensure that the vehicle _2, the vehicle from the most negative slope during braking to trigger an emergency stop acceleration beta] _2, is determined after Calculation method of car EBI speed.
4. The method according to claim 1, wherein the step 32 comprises:

   When τ ₁ <δ ₂ +ε ₂ , the constraint condition for calculating the initial speed of the rear vehicle, that is, v ₂ (t ₀ )≤f ₅ (t) and v ₂ (t ₀ )≤f ₄ (t _m1 ), the rear vehicle The calculation method of EBI speed is: E ₂ (t ₀ )=min(f ₅ (t), f ₄ (t _m1 ))

   When δ ₂ +ε ₂ ≤τ ₁ , and (α ₁ +β ₁ )-(α ₂ +β ₂ )>0, calculate the constraints of the initial speed of the rear vehicle respectively, v ₂ (t ₀ )≤f ₅ ( t), v ₂ (t ₀ )≤f ₄ (t _m1 ), v ₂ (t ₀ )≤f ₄ (t ₁ ) and v ₂ (t ₀ )≤f ₃ (t _n1 ); The calculation method is: E ₂ (t ₀ )=min(f ₅ (t), f ₄ (t _m1 ), f ₄ (t ₁ ), f ₃ (t _n1 ))

   When δ ₂ +ε ₂ ≤τ ₁ , and (α ₁ +β ₁ )-(α ₂ +β ₂ )≤0, calculate the constraint conditions for the initial speed of the rear vehicle, namely v ₂ (t ₀ )≤f ₅ (t), v ₂ (t ₀ )≤f ₄ (t _m1 ) and v ₂ (t ₀ )≤f ₄ (t ₁ ), the calculation method of the EBI speed of the following vehicle is: E ₂ (t ₀ )=min( f ₄ (t ₁ ), f ₅ (t), f ₄ (t _m1 )).
5. The method of claim 4, wherein:

   Among them, formula 1:

   

   in,

   

   

   In formula 2,

   

   in,

   

   

   Formula 3:

   

   

   Formula 4:

   

   in,

   

   
6. A train safety tracking protection device based on relative speed, characterized in that it includes:

   The first generating unit is used to track the running vehicle in front and the rear vehicle to obtain the safety space-time trajectory information of the train during the parking process by using the electronic map and the autonomous speed measurement and positioning information in combination with the train performance; the safety space-time trajectory information includes: position curve over time;

   an acquisition unit, using the communication method between vehicles, the rear vehicle obtains the safety space-time trajectory information of the front vehicle;

   Solving unit, the rear vehicle combines the safety space-time trajectory information of the front vehicle and the rear vehicle, establishes a safety condition according to the constraint that the position of the rear vehicle cannot exceed the position of the preceding vehicle at any time, and solves the emergency of the rear vehicle Braking triggers EBI speed;

   A comparison unit, the rear vehicle compares _{whether the current measured speed v 2} (t ₀ ) of the rear vehicle exceeds the EBI speed E ₂ (t ₀ ) of the rear vehicle; if v ₂ (t ₀ )>E ₂ (t ₀ ), the emergency braking command is output to make the rear vehicle decelerate to a stop.

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